Effect of Dy substitution for La in La0.7Ca0.3MnO3 perovskite

AC susceptibility, resistivity and dc magnetization measurements on the (La0.757Dy0.243)(0.7)Ca0.3MnO3 perovskite reveal a clear departure from the well-behaved (collinear) ferromagnetic nature observed in the parent material La0.7Ca0.3MnO3 at low temperatures. Neutron diffraction structural study shows that the buckling of the MnO3 octahedra increases with the Dy substitution. This in rum gives a weaker double exchange (ferromagnetic) interaction, as the transfer integral, t(o), describing the hopping of e(g) electrons between Mn3+ and Mn4+ decreases resulting in the observed deterioration of ferromagnetism and metallic conduction. (C) 2001 Elsevier Science BY All rights reserved.